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H. w. MATHESON. ELECTROLYTIC CELL.

APPLICATION FILED APR. 15, 191B- 1;,3T9A66O Patented. May 24L, 1921.

43 47 Fkg. 2 4a 2/ 385 5/ /& a ww To all whom. itmay concern:

UNHTED STATES E ATENT @FFHQE.

ELECTROLYTIC CELL.

Specification of Letters Patent.

Patented May 24, 1921.

Application filedApril 15, 1918. Serial No. 228,675.

Be it known that I, HOWARD W. MATHE- soN, a subject of the King of Great Britain,

and resident of the town of Shawenegan Falls, in the Province of Quebec and Dominion of Canada, have invented certain new and useful Improvements in Electrolytic Cells, of which the following is a full, clear, and exact description.

This invention relates to improvements in apparatus for oxidizing mercury, and the object of the invention is to provide a simple, efiicient, durable and safe apparatus for carrying out the oxidation of mercury by electrolytic action.

The device consists briefly of a shallow metal pan insulated from the earth, and designed to contain the mercury to be oxidized in a layer of suitable depth in the bottom of the pan. A. stirring device is provided just above the level of the mer cury, and above the stirring device a metal cathode having openings for the escape of gas. Means are provided for connecting ,one side of an electric circuit to the pan and the opposite side to the cathode. Means are provided for supplying mercury and the electrolyte liquid to the pan and for gaging the amount of each. hood is provided over the pan to collect gases rising from the action and upper and loweroutlets are provided from the hood for the escape of the lighter and heavier gases. Above the hood, a variable speed drive for the stirrer is located.

In the drawings which illustrate the invention;

Figure 1 is a vertical sectional view through the center of a cell.

Fig. 2 'is a fragmentary plan view. Fig. 3 is a front elevation of the varlable speed, drive.

Referring more particularly to the drawings, 11 designates a circular pan, preferably of cast iron having suitable radial stifiening ribs 12 on the outside of the bottom and circumferential ribs 13 on the mside of the bottom. The sides of the pan are protected by a lining 14. of concrete or other suitable material coated with asphalt or other suitable material, which will be impervious to the action of the electrolyte used. The annular ribs 13 form guides for accurately placing the lining wlth respect to the center of the pan, supports for the lining, and also dams to hold mercury into the active area of the cell. The bottom of the pan is provided externally with bosses 15 threaded for the reception of leveling screws. The bottom of the pan is also prov1ded externally with means 16 for attach- 111g an electric conductor 17. A support 18 is provided traversing the to of the pan diametrically. The. hub 19 of the cathode is suspended from this support and is provided with means 20 for attaching the other conductor 21. A plurality of radially disposed bars or spokes 22 are welded or otherwise suitably secured to the hub, and extend to the lining 14, where they may if desired rest on a step 23 in the lining. Blades 24- are secured between the spokes. These blades preferably overlap slightly and are inclined from the center to the circumference of the pan, so as to leave spaces 25 therebetween for the escape of gas. The blades are preferably secured to the arms by means of bolts and clamping bars 26. The whole cathode is preferably constructed of iron or steel and is preferably nickel plated large insulators 29 of porcelain or other suitable material stand. These insulators in turn support metalthrust blocks 30, in'

which the leveling screws 31 bear. The supporting columns under the pan are preferably three in number and disposed equidistant from the center of the pan, so that the pan is securely supported and may be accurately leveled.

A rotary stirring device 32 is provided in the pan between the bottom and the cathode. This device is preferably provided with blades pitched similarly to propeller blades and traveling in a horizontal plane, so that an up and down circulation of the electrolyte will be obtained as well as a circular or swirling motion.

A hood 33 is provided a suitabledistance above the pan supported on columns 34. This hood is preferably provided with a back 35 extending to the top of the pan, and a front 36 which may be opened to give access to the pan. This front 36 may conveniently take the form of a roller curtain. The hood is provided at the top with an outlet 37 for gases and at the bottom with an overflow outlet 38 for electrolyte.

Above the hood, a power shaft 39' is mounted in suitable bearings 40 and also a counter shaft 41 having large and small sprockets 42 and 43 respectively, revolubly mounted thereon. These sprockets are connected by chains 44 with sprockets 45 on the power shaft. A clutch member 46 is slidably but irrevolubly mounted on the counter shaft and may be thrown into engagement with either the large or small sprocket, so that the counter shaft may be driven at either of two speeds. The counter shaft is provided with a pinion 47 meshing with a gear 48 mounted on a vertically disposed shaft 49, having a bearing 50 in the hood and an insulating bearing 51 in the support 18. This shaft is connected at its lower end with the stirring device 32 and an insulator 51 is provided in the shaft to guard against accident in the event of the stirring device 32 touching either the mercury or the cathode.

The shaft 49 is screwed and keyed to the stirrer, so that the vertical height of the stirrer with respect to the pan may be adjusted.

A valve controlled pipe line 52 is provided for supplying electrolyte to the cell and also a valve controlled pipe line 53 for supplying mercury to a small pot 54, located adjacent the cell and having a valve controlled discharge 55 leading into the cell. By filling the pot, it is possible to gage the exact amount of mercury supplied to the cell. The pan is provided with a gage glass 56 of ordinary construction, which will show the levels of mercury and electrolyte in the cell. A valve controlled outlet 57 from the bottom of the pan is provided and is supplied with a flexible pipe 58 designed to discharge the contents of the cell into a trough 59 or other desired receptacle. This trough is provided with a removable cover 60 preferably made up in sections. The cell is also provided with a valve controlled draw-01f a short distance above the surface of the mercury.

The device as thus far described relates only to a single cell. It will be understood, however, that in an oxidizing plant of any size, there will be a large number of such cells connected up in batteries. The cells are preferably connected in rows and for economy of floor space, there may be two rows placed back to back and forming either a single battery or two separate batteries. In the case of cells arranged back to back in a single battery, the back 35 of the hood will be unnecessary, but if the arrangement includes two separate batteries, the back 35 will be necessary so that they may be operated independently.

The operation of the device is extremely simple. The device, having been properly leveled, mercury is admitted to the pan to form a layer approximately three-quarters of an inch deep, so that the stirrer will just the pan, forms the anode. The lining l4 prevents the sides of the pan acting as an anode, so that the entire electrolytic action is confined to the surface of the mercury. The clutch 46 is adjusted to drive the counter shaft 41 at its low speed and, as soon as the current is turned through the cell, the stirrer is started and revolves slowly in the electrolyte just clear of the surface of the mercury, so as to keep up both a swirling movement of the electrolyte in a horizontal plane and a vertical movement due to the pitch of the stirrer blades. This motion of the electrolyte serves to wash away the oxid from the surface of the mercury as fast as it forms and thus leave a clear metallic surface for the oxidation to continue. The gases rising from the action pass through between the blades of the cathode, and escape through the fines 37 and 38. Mercury ma be added from time to time, according as it is oxidized, so as to maintain nearly a constant amount of mercury in the pan. When the action is continued until the electrolyte is very heavy with the oxid formed, the clutch 46 is shifted, so that the stirrer rotates at much higher speed, and any sediment of oxid is thoroughly stirred up into the electrolyte. The electrolyte can now be drawn off into the trough 59 through the pipe 61 for further treatment to separate the oxid from it.

Having thus described my invention, what I claim is 2-- 1. In a device of the class described, an electrolytic cell, a canopy thereover including top and back portions, upper and lower outlets for said canopy, and a roller curtain movable into position to close the space between the canopy and the cell.

2. In a device of the class described, an electrolytic cell, means for insulating said cell from the earth, means for leveling the cell, a canopy over said cell electrically independent thereof, a stirring device in the cell out of electric contact therewith, and means above the canopy for operating said stirring device whereby the operating means is not electrically charged.

3. In a device of the class described, an electrolytic cell, a measuring tank mounted on the cell having a valve controlled discharge leading thereinto, drainage outlet from the cell and a fluid level gage between the outlet and the upper portion of the cell arranged to indicate the level of liquid admitted from the tank.

4:. In a device of the class described, an electrolytic cell comprising a flat bottomed pan, and annular ribs on said pan adjacent the periphery thereof excluding mercury from the sides of the pan.

5. In a device of the class described, an electrolytic cell comprising a flat shallow pan forming one electrode of the cell, and a cathode having gas passages therethrough, substantially covering the bottom of the cell and insulated therefrom.

6. In a device of the class described, an electrolytic cell comprising a metal receptacle, means for connecting an electric conductor thereto, an electrode suspended in the receptacle, means preventing electric discharge between said electrode and the sides of the receptacle and a stirring device betwfien the electrode and the bottom of the ac 7. In a device of the class described, an electrolytic cell comprising a flat pan, an-

nular ribs on the bottom of said pan adapted to exclude a layer of mercury from the sides of the pan, a cathode suspended above the mercury layer, and means for confining electric discharge between the cathode and the mercury.

8. In a device according to claims 4 0r 7, a stirring device adapted to sweep the surface of the mercury.

9. In a device of the class described, a receptacle insulated from the earth, a canopy thereabove electrically connected with the earth, an electrode in the receptacle insulated therefrom, a stirring device in the receptacle, and drivingmeans therefor above the canopy insulated from the receptacle and electrode.

10. In combination with a device according to the preceding claim, a curtain adapted to close the space between the receptacle and canopy.

In witness whereof, I have hereunto set my hand.

HOWARD W. MATIESON. 

